1. Field of the Invention
This invention relates generally to knee braces.
2. Prior Art
Knee braces are known for reducing stress on a knee by spreading forces over a wide area on the leg. They fall into two categories: flexible braces, and rigid braces. A flexible knee brace disclosed in U.S. pat. No. 5,512,039 to White is comprised of a tubular sleeve surrounded by flexible reinforcing straps. It is for tightly holding the muscles and ligaments in position, and also for keeping warm. It does not provide any structural support, so the knee is still prone to injury from excess stress. It must be wrapped tightly to stay in position, so that it is uncomfortable to wear. Although it is flexible, the sturdiness of its materials makes it difficult to bend, so that it hinders leg movements.
A rigid brace disclosed in U.S. pat. No. 5,857,988 to Shirley is comprised of a pair of upper rods connected to a pair of lower rods by respective hinges. The rods are strapped to opposite sides of a leg with the hinges positioned on the sides of the knee. The loads on the ligaments can be varied by adjusting the tension of a pair of cables zigzagging between the upper and lower bars at the front of the brace. The rods are connected by horizontal straps at the back of the brace. The asymmetry between the front and the back of the brace results in uneven load distribution wherein some parts of the leg are subject to higher forces than others. Further, the cables are disconnected from each other. They act independently of each other, so that they do not help resist lateral forces.
A similar brace disclosed in U.S. pat. No. 5,782,785 to Herzberg includes horizontal straps connecting the rods on opposite sides of the leg. The horizontal straps do not help resist lateral forces.
Another rigid brace disclosed in U.S. pat. No. 5,797,864 to Taylor includes rods on only one side of the leg. The knee is tensioned against the rods by a single helical strap connected between the upper and lower rods and wrapped around the other side of the knee. The back of the knee is crossed by the strap, which hinders bending of the leg. Because of the severe asymmetry of the brace, lateral forces tend to twist the knee and loosen the brace.
The resistance of prior art rigid braces against lateral forces depends entirely on the rigidity of the rods. The straps between the rods do not contribute to lateral rigidity. The rods can be made thick and strong enough to provide enough lateral rigidity, but the benefits are offset by an accompanying increase in bulk and weight. The discomfort associated with prior art rigid braces makes them especially undesirable to wear prior to injury for injury prevention.
Accordingly, the objectives of the present truss body joint brace are:
to reduce stress on a body joint by spreading lateral forces over a large area on a limb;
to strongly resist lateral forces;
to minimize interference with limb movements;
to be comfortable to wear;
to stay in position without a tight fit;
to be easily adjustable for fitting different wearers;
to be easily adjustable for accommodating changes in the shape or size of the limb;
to be very lightweight for comfort;
to be compact and thus cosmetically pleasing; and
to be inexpensive.
Further objectives of the present invention will become apparent from a consideration of the drawings and ensuing description.
The present truss body joint brace includes a pair of upper bars for positioning on opposite sides of an upper portion of a limb, a pair of lower bars for positioning on opposite sides of a lower portion of the limb, and a pair of hinges for positioning on opposite sides of a joint on the limb and connected between respective upper bars and respective lower bars. A pair of upper front crossed straps and a pair of upper back crossed straps are connected between the upper bars. A pair of lower front crossed straps and a pair of lower back crossed straps are connected between the lower bars. A flexible tubular upper sleeve is positioned between the upper bars, and a flexible tubular lower sleeve is positioned between the lower bars. The straps are adjustable in length for a snug fit. The bars, crossed straps, and the limb cooperate to form a truss structure that strongly resists lateral forces and protect the body joint from injury.